Power steering apparatus



W. GEHRIG rowan s'rmannm arrm'ms Nov. '26, 1929.

Filed Jan. 23, 1926 Original Filed Jan. 23. 1926 3 Sheets-Sheet l d I Inventor Whiter 62%? Attorney w. *GEHRIG Nov. 26, 1929.

POWER STEERING APPARATUS Filed Jan. 23, 1926 Original Filed Jan. 23, 1926 3 Sheets-Sheet 2 Attorney W. GEHRIG Nov. 26, 1929.

rowan STEERING APPARATUS Filed Jan. 23, 1926 Original Filed Jan. 23, 1926 3 Sheetsheet 3 Inventor FVd/f/ 6d Attorney Reissued 26, 1929 PATENT OFFICE WALTER GEHBIG, F DETROIT, MICHIGAN YOWER STEERING APPARATUS Original No. 1,647,404, dated November 1, 1527, Serial No 83,404,.fl1ed January 23, 1926. Application for reissue filed February 15, 1928. Serial No. 254,595.

The present invention pertains to a steer ing apparatus for vehicles and is applicable particularly to heavy automobile trucks, buses or other motor vehicles carrying ha]- loon tires. 7

The principal object of the invention is to.

provide mechanical means for facilitating the steering of such vehicles. It has been found that motor vehicles equipped with the so called balloon tires are much more difficult to steerthan vehicles carrying tires of smaller diameter and greater pressure, and a greater turning of the steering wheel is reguired for making the same size of turn. nother difficult arising out of the use of balloon tires is t met there is a greater tendency of the front wheels to wobble. Motor buses and trucks at present inuse are so constructed that three to three and a half revolutions of the steering Wheel are required for making the maximum turn. The driver of such a vehicle, in order to operate the same in this manner, is required to slow down in approaching an intersection in order to 5 allow s'uflicient time to turn the steering wheel. In case of accident or an unforeseen obstacle, it isimpossible for a heavy vehicle at high speed to be turned sharply to avoid danger.

The resent invention overcomes the foregoing 1 ifliculties By providing an apparatus whereby a sharp turn may be quickly made without unreasonable exertion on the part of the driver. Even in the case of the large 36 balloon tires, a vehicle equipped with the invention requires no more turning of the steering wheel than vehicles having smaller.

tires under greater pressure.

The invention consists essentially of double pistons mounted. in cylinders and linked to the forward wheels of the vehicle, in combination with valve mechanism operable from the steering post for controlling a flow of pressure to the'ends of the cylinders.

A further feature of the invention is that the double pistons are normally under balanced pressure in the c linders', whereby wobbling of the front w ieels or deflection on striking obstacles is substantially prevented. I

- in section and The invention is fully disclosed in the following description and in the accompanying drawings, in which:

Figure 1 is a perspective view of the device applied to the steering post of a vehicle; Figure 2 is a front elevation of a vehicle equipped with the invention;

' Figure 3 is a plan View of the device as applied to a vehicle; 7

Figure 4 is a plan View of the forward part of a vehicle equipped with the-invention, the wheel control cylinders being shown Figure 5 is a sectional view of the remaining part of the apparatus, parts being shown in elevation;

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout. The appllance constituting this invention 'is connected with the forward wheels lot the vehicle, orthose wheels which are designed to be steered from the usual steering post 2. A pair of wheel control cylinders 3 and 4 are supported near the wheels 1, preferabl on the axle. The cylinders contain doub e pistons 3', 3 and 4, 4" respectively, each 'pair being joined by a rod -6. To one piston of each pair is pivoted a finger 7 to which .in turn is pivoted one end of a link 8, the remaining end of which is rigidly secured as at 9 to an arm 10 which is connected to the brake drum 11, by means-of another link 12 connected pivotally to the members 10 and 11.

This mechanism is controlled, by the apparatus hereinafter described, from the steering post 2 which is connected by a worm and pinion (not shown) to an arm 13 pivotally mounted in a housing 14 clamped to the post 2. The lower end of the'arm 13 carries a .ball 15 which is received between two blocks 16 and 17slidably mounted in a casing 18 supported at any convenient position. The two blocks 16 and 17 are pressed against the ball 15 by means of springs 19 bearing age inst these blocks and against the ends 20 of the cylinder 18. Stubs 21 secured in the ends 20 limit the outward movement of the blocks 16 and 17.

These chambers contain the va ves and 26' having stems 27 slidably received in the bushing 28 disposed in the intermediate portion 29 of the cylinder. The valve heads are normally pressed towards their seats by rings 30 mounted in the compartments. Between the absorber cylinder 23 and the linder 18 are mounted a pair of valve cylin ers 31 and 32 which are associated with the blocks 16 and 17 in the manner hereinafter set forth. Although the several cylinders are illustrated as separated in Figure 5 for convenience of description, they ma be actually embodied in a single casting as s own in Figure 1. A The valve cylinders contain partitions 33 and 34 dividing the cylinders into primary compartments 31, 32 and secondary comparts 31" and 32". Each primary compartment contains ajvalve 35 co-operating with a seat 36 and having a stem 37 pressed against an arm-38 by the pressure of a spring 39 bearing against the partitions 33 or 34. Said arm 38 is rigidly secured to the correspond in block 16 or 17. v

ach secondary compartment contains also a valve 40 co-operating with a seat. 41 and having a stem 42 separate from but adapted to engage the primary valve 35. The second? aryvalves are also normally pressed towards their seats by springs 43 engaging the outer ends of the cylinders 31 and32.

The primaiy ocompartments 31 and 32' communicate seats with the ends of the cylinder 23 through pipes 42 and 43. The secondary compartments at one side of the valve seatcommunicate with fluid supply pipes 44 and 45, the former being branc ed as at 44. and 44 to connect with oneend of the the other pipe is branched as at '45 and 45 cylinders. The primary cy nders, at the sides of their valve seats 0 posite the pipes 42 and 43, are connected through by-p'asses 46 and 47 into the lines 45 and 44 respectively. The secondary compartments, at the sides of their valve seats opposite the pipes 44 and 45,

are formed with exhaust ports 48 and 49 respectively leading to the atmosphere.

The apparatus is illustrated in Figures 4 and 5 with the parts in neutral position. The

pressure from the tank 22 causes the valves gear (13).

In one side of their valve linder 3 and" the remaining end of the cyhnder 4, while 25" and 26" to uncover their respective seats, whereupon the pressure fluid flows through pipes 42 and 43 to the primary compartments.

The valve seats 36 are held normally slightly of cylinder 3 and the forward end of cylinder 1 '4. I The equal pressures on both sides of-the double pistons obviously causes no displacement of the pistons. p

In the operation of the device, assuming that the vehicle is to be steered to the right, the driver turns the steering wheel in the usual manner. Ordinarily considerable force is required to turn the heavy wheels ofa' truck, and for a large turn several revolutions of the steering post are often necessary. The gearing placed within the housing 14 is constructed to swing the arm 13 to the right, with reference to Figures 1 and 5, when the steering wheel is turned to the right. The spring which presses the block 17 against the ball 15- will be. compressed to a degree depending upon the resistance of the wheels 1 against the pressure from the manually operated steering The two blocks 16 and 17 will therefore slide accordingly towards said conipressed spring and the corresponding move-' ment of the arms 38 Will actuate the valves 35 and 40. The movement of the arms 38 causes the valve seat 36 in the cylinder 31 to be closed, and the flow of pressure through the pipe 46 to the forward end of cylinder 3 and rear end of cylinder 4 is obstructed. At the same time the primary valve invcylinder 32 is retracted and brought into engagement with the stem of the secondary valve, whereupon the secondary valve seat in thecylinder is opened. The compartment 32 is thus brought into free communication with the exhaust port 49, and exhaust is (permitted from the forward end of: cylm er 3 and rear end of cylinder 4.

in which the pressure has been relieved, whereupon the two wheels 1 are turned in unison throughthe linkages connecting them.

to the double-pistons. Obviously a similar operation takes place when the vehicle is to be steered to theleft.

From the foregoing description it will be Pressure fluid is still supplied through.

pipe 43 to the primary corn artment of cyl-' to connect with the remainin ends of these in move the double pistons towards the ends a erted on t understood that the pressure difference in the two chambers of each wheel control cylinder is constantly depending from the amount and the duration of opening of either one of the two exhaust valves 40. This opening of the exhaust valves in turn is constantly depending from the amount and the duration of compression of either one of the two springs 19. The pressure exerted on the wheels by vthedoublepistons is therefore practicall proportionate to the pressure exlle wheels by the manually operated steering rod 18 which connects the steering arm 13 with the wheels 1.

When one of the secondary valves 40 is open and releases the fluid pressure from the two cylinder chambers connected thereto, then the movement of the piston and the corresponding flow of fluid under pressure from the tank 22 to the opposed cylinder chambers will open the relative oneway valve (25 or 26 This one-way valve wil close again as soon as the pistons in the wheel control cylinders 3 and 4 are under balanced fluid pressure after the valves and have moved back to neutral posi- -tions.

Back pressure from the cylinder chambers I 3 and 4 will not open the spring pressed one-way valves 25 and 26". Back flow of fluid from the cylinder chambers 3 and 4 and the fluid controlling device (35, 31,, 32') is limited to the fluid being able to flow through the by-pass or apertures (25 and 26) associated with each one-way valve.

For very slow and minor steering adjustments whlch are not suflicient' to compress the springs 19 so as to establish contact between the stems of the secondary valves and the heads of the primary valves, the

apertures 25 and 26 in the valves 25 and 26" respectively diminish the resistance to the displacement of the double pistons. Y

Quick sidewise movements of the wheels, such as wheel-wobbling, however, will be dampened as the comparatively small apertures 25 and 26 in the one-way valves 25 and 26' do not permit free back flow of fluid from the cylinder ends which are diminished in size by the corresponding movement of the double pistons. Increased com-- pression of the fluid must therefore occur in those cylinder chambers. This increased compression acts as resistance to wheel wobbling or to deflection of the wheels caused by irregularity in the road.

Should this increased compression not be suflicient to control the wheels, for example if one of the wheels'is deflected by a rock or rut, then the valve mechanism is automatically thrown in action. The Wheel movement will cause corresponding movement of the steering rod 18, the movement of which compressses either one of the springs 19 as the steering arm 13 is irreversible. Consequently the valves will be actuated in the same manner as if the manually operated steering gear would be actuated to counteract to said wheel deflection.

The extent of wheel movement which is not suflicient to throw the fluid pressure controlling valve mechanismin action is determined by the play or lost motion of the manually operated steering gear plus the clearance between-the head of the primary valve 35 and the stem of the secondary valve 40.

While a specific embodiment of the invention has been illustrated and described, it is to .be understood that various alterations in the details of construction may be made without departing from the spirit of the invention as indicated by the appended claims.

Having thus fully described the invention, what I claim as new and desire to protect by Letters Patent 1. In a power steering apparatus, the combination with a motive fluid supply and a fluid motor connected with the steered part, of a fluid controlling device comprising a pair of valvecylinders, partitions dividing each of said valve cylinders into a primary and secondary compartment, a valve in each primary compartment, operative connection between the primary valves and. the manual operated steering mechanism, a secondary valve in each secondary compartment and engageable by the primary valve in the same valve cylinder, conduits connecting the primary compartments with the motive fluid supply, exhaust means associated with the secondary compartments, conduits in fluid connection with the fluid motor at one endand with the primary valve of one valve cylinder and the secondary valve of the other valve cylinder at the other ends.

2. In combination with the forward wheels of a vehicle, a wheel control cylinder containing pistons linked to said wheels, valve cylinders, partitions in said valve cylinders dividing the same into two compartments, a valve in each compartment, an operative con- -nection between the valves in each cylinder and the steering mechanism o'f'the vehicle, one of the com artments of each valve cylinder being in uid communication with one of the ends of the control cylinder, and means for admitting pressure fluid into the remainof the control cylinder, secondary Valves in v the secondary compartments, conduits connecting said secondary compartments with the remaining end of the control cylinder,

cylinders and linked to the wheels, a pair of valve cylinders, partitions in said valve cylinders dividing the same into two compartments, a valve in each compartment, an oper-. ative connection between the'valves and each cylinder and the steering mechanism of the vehicle, one of the compartments of each valve cylinder being in communication with one of the ends of each control cylinder, and means for admitting pressure fluid into the remaining compartments.

5. In combination with the forward Wheels of a vehicle, a air of wheel control cylinders supported by t e vehicle, iston's mounted in said cylinders and linke to said wheels, a. pair of valve cylinders, partitions dividing each of said valve cylinders into a primary and secondary compartment, a valve in each primary compartment, operative connection etween the primary valves and the steering mechanism of the vehicle, conduits connectmg the primary compartments with one end fof each control cylinder, secondary valves in the secondary compartments, conduits connecting the secondary compartments with the remaining ends of the control cylinders, said secondary valves being engageablc by said' primary valves, exhaust means associated with said secondary compartments, and means for supplying pressurefluid to 'said primary compartments.

6. In combination with the forward wheels of avehicle, a pairof wheel control cylinders supported by the vehicle, pistons inounted in said cylinders and linked to said wheels, a pair of valve cylinders, partitions dividing each of said valve" cylinders into a primary andsecondary compartment, a valve in each psimary compartment, operative connection between the primary valves and the steering mechanism of the vehicle, conduits conn'ecting the primary compartments with one end of each control cylinder, secondary valves in the secondary compartments, conduits connecting the secondarycompartments with the remaining ends of the control cylinders, said secondary valves'bein'g engageable by said primary valves, exhaust means associated with said secondary compartments, an absure fluid tank connected to said absorber cylinder intermediate said valves.

7 In combination with the forward wheels of a vehicle, a wheel control cylinder containing pistons linked to said wheels, valve cylinders, partitions in said valve cylinders dividing the same into two compartments, a valve in each compartment, and yieldingly operative connection between the valves in each 0 *linder and the steering mechanism of the ve icle, one of the compartments of each valve cylinder being in fluid communication with one .of the ends of the control cylinder and means for admitting pressure fluid into the remaining compartments. i

8. In combination with the forward wheels of a vehicle,a pair of wheel control cylinders supported by the vehicle, pistons mounted in said cylinders and linked to said wheels, a pair of valvecylinders, partitions dividing each of saidvalve cylinders into a primary and secondary compartment, a valve in eac primary compartment, operative connection between the primary valves and the steering mechanism of the vehicle, i yielding pressure transmitting means interposed in said steering mechanism, conduits connecting the pri mary compartments with one end of each con trol cylinder, secondary valves in the secnected with the steered part, of a fluid conduit'connecting the motive fluid supply with said fluid controlling device, a one-way valve in said conduit permitting flow of fluid from said fluid supply to said fluid controlling device but obstructing back flow of fluid from said fluid controlling device -to said motive fluid supply, a b'y-pass associated with said one-way valve and in fluid connection with said fluid conduit on both sides of said onewaiy valve. a

n testimony whereof, I have hereunto set my hand.

. WALTER GEHRIG.

structable port therethrough, an a pres- 1 

